FlexSys ACTE flap technology bridges gaps in wing for a seamless surface. (Flexsys image) › View Larger Image The Adaptive Compliant Trailing Edge, or ACTE, experimental flight research project is a joint effort between NASA and the U.S. Air Force Research Laboratory to determine if advanced flexible trailing-edge wing flaps can both improve aircraft aerodynamic efficiency and reduce airport-area noise generated during takeoffs and landings.

The experiment is being carried out on a modified Gulfstream III (G-III) business aircraft that has been converted into an aerodynamics research test bed at NASA's Armstrong Flight Research Center.

The ACTE project involves replacement of both of the G-III's conventional 19-foot-long aluminum flaps with advanced, shape-changing flaps that form continuous bendable surfaces. The flexible flaps are made of composite materials to a patented design from FlexSys, Inc.

This modified Gulfstream III is the test bed aircraft for the ACTE flexible-flap research project. (NASA Photo) › View Larger Image When conventional flaps are lowered, gaps exist between the forward edge and sides of the flaps and the wing surface. The ACTE flaps will be gapless, forming a seamless transition region with the wing while remaining attached at the forward edge and sides. The improved flap should eliminate a major source of airframe noise generation.

If successful, this experiment will enable aircraft using such flaps to be significantly quieter during takeoff, approach and landing. The ACTE project is in line with the goals of the Environmentally Responsible Aviation, or ERA, project under the Integrated Systems Research Program of NASA's Aeronautics Research Mission Directorate. The directorate and the Air Force Research Laboratory are jointly funding the effort.